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Rules actions that add new field collection items to a node fail to work when Node access user reference is enabled. The items aren't added, and there's a message saying "Access violation! You have insufficient access permissions to edit this configuration.".
The acting user is the owner of the node, and is even allowed to edit all nodes of that type. Node access user reference is not used on any field (not on that node type, nor any other). There are entity reference fields on the site (but no user reference fields).
Find out what is causing this problem.
User interface changes